(a) Technical Field
This invention relates to a rechargeable battery, and in particular, the battery includes high density capacitors for storing electrical charges and circuitries for battery charging and discharging functions.
(b) Description of the Related Art
Various rechargeable batteries are known in the art. These batteries include chemical accumulator based such as lithium-ion, nickel-cadmium, nickel-metal hydride, and so forth. The chemical accumulators basically comprise two electrode plates and electrolyte in between the plates. These rechargeable batteries have limited operational lifetime due to irreversible chemical changes that gradually take place during charging and discharging. Since these batteries contain toxic chemical they are not environmental friendly after the battery life for disposal.
In recent development of magnetic capacitors by Northern Lights Semiconductor Corporation (NLSC), high capacitance density has been demonstrated in magnetic capacitors. With the high capacitance density and low leakage current, magnetic capacitors open up a brand new field of applications for electrical power storage and management. For instance, in U.S. Pat. No. 7,911,187, Lai and Fong taught to apply magnetic capacitors for passive regulation and protection of an electronic subsystem in System-in a-Package (SIP).
In this invention, we fabricate rechargeable batteries with high density capacitors and Integrated Circuit (IC) on semiconductor substrate. The battery size and weight are dramatically reduced with very high storing power density. For instance, the charging capacity of a rechargeable lithium-ion battery available in mobile devices is around 2000 mA-hour, equivalent to 7200 Coulomb. For a charging voltage of 5V and maximum discharging voltage of 3 V in one of our designs, the areas of the magnetic capacitor are only 36 mm2 for a magnetic capacitor with capacitance density of about 100 μF/μm2, where areas=7200 Coulomb/(5V−3V) (charging voltage−maximum discharging voltage)/100 F/mm2 (capacitance density). The weights of the companion ICs and magnetic capacitors are around the same weights of a common IC chip with the compatible chip sizes, which weights less than a grain.
In contrast to chemical accumulator based rechargeable battery, the rechargeable batteries are environmental friendly because that there are no toxic chemical elements in the batteries. Also due to near infinite numbers of charging-discharging cycles of the magnetic capacitors, the rechargeable batteries exhibit almost infinite number of rechargeable cycle life. The self-discharging rate of the conventional chemical accumulator rechargeable batteries, for example, lithium-ion batteries, are around 8% of its storing capacity per month. Because the total leakage current of the magnetic capacitors and IC with a careful design can be down to ˜several μA, the newly designed rechargeable batteries can have very long cell charge storage life up to tens of years.
In another aspect of the present rechargeable batteries, the rechargeable batteries can provide multiple voltage sources for various current requirements. Many electronic systems require multiple power sources for various sub-system functions. For example, a mobile device may have several sub-systems: Micro-Processor-Units (CPU), memory units, Radio Frequency (RF) units, display and human interface units. All the sub-system units may require various voltages and currents. The conventional rechargeable batteries can only provide a single power source. To meet the multiple power requirements for an electronic system, a companion power IC with multiple outputs and a battery are usually required. The present rechargeable batteries can provide multiple power sources for the entire power requirements of electronic systems in one single battery.